Liquid crystal display device

ABSTRACT

It is an object to provide a display having high visibility and a transflective type liquid crystal display device having a reflection electrode having a concavo-convex structure formed without especially increasing the process. During manufacturing a transflective liquid crystal display device, a reflection electrode of a plurality of irregularly arranged island-like patterns and a transparent electrode of a transparent conductive film are layered in forming an electrode having transparent and reflection electrodes thereby having a concavo-convex form to enhance the scattering ability of light and hence the visibility of display. Furthermore, because the plurality of irregularly arranged island-like patterns can be formed simultaneous with an interconnection, a concavo-convex structure can be formed during the manufacturing process without especially increasing the patterning process only for forming a concavo-convex structure. It is accordingly possible to greatly reduce cost and improve productivity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device of apassive matrix type and an active matrix type. Particularly, theinvention relates to an electrode structure of a transflective typeliquid crystal display device having both functions of a transmissiontype and a reflection type.

2. Description of the Related Art

In recent years, by explosive spread of a portable information terminalrepresented by a cellular phone, there is needed a display capable ofdealing with light-weighted formation, low power consumption and achange in an environment of use.

Further, in views of thin film formation and light-weighted formation, aliquid crystal display device or an organic EL display device isrepresentatively promising.

Power consumption of a transmission type display device isinconsiderable for driving only a display. However, a liquid crystal perse does not emit light and therefore, a back light is needed fordisplaying as a display. For use of a cellular phone, an EL back lightis generally used, however, power is additionally needed for the backlight and a specific characteristic of low power consumption of a liquidcrystal is not fully utilized, which are disadvantageous in low powerconsumption. Further, although in a dark environment, display of adisplay is viewed with excellent contrast, in an ordinary brightenvironment, the display is not viewed so well and there is a drawbackin adaptability in accordance with the environment of use both in casesof an upper emitting type and a lower emitting type.

Further, the organic EL display device is characterized in which adisplay element per se emits light. Although power consumption thereofbecomes larger than that of a reflection type liquid crystal displaydevice, the power consumption is smaller than that of a transmissiontype liquid crystal display device (having back light). However, similarto the case of the transmission type liquid crystal display device,although in a dark environment, display of a display is viewedexcellently, in an ordinary bright environment, the display is notviewed so well and therefore, there is still a drawback in adaptabilityin accordance with an environment of use both in cases of the upperemitting type and the lower emitting type.

Further, the reflection type liquid crystal display device utilizesoutside light from an environment as light for display. On the side ofthe display, the back light is not basically needed, only power fordriving a liquid crystal and a drive circuit is needed and therefore,positive low power consumption is achieved. Further, quite contrary tothe former two, although in a bright environment, display of a displayis viewed excellently, in a dark environment, the display is not viewedso well. Considering the use of a portable information terminal, theportable information terminal is mainly used outdoors and there isfrequently a case of viewing the display in a comparatively brightenvironment, however, this is still insufficient in terms ofadaptability in accordance with an environment of use. Therefore,locally, a reflection type display device integrated with a front lightis on sale such that the display can be carried out even in a darkenvironment.

Hence, attention is given to a transflective type liquid crystal displayhaving advantages of both of a transmission type and a reflection typeliquid crystal display device by combining the device. In a brightenvironment, a characteristic of the reflection type of low powerconsumption and excellence in visibility under the environment isutilized, meanwhile, in a dark environment, a characteristic ofexcellence in contrast provided to the transmission type is utilized byusing a back light.

A transflective type liquid crystal display device is disclosed inJP-A-11-101992. The device is a reflection and transmission type(transflective type) liquid crystal display device. More concretely, byfabricating a reflection portion for reflecting outside light and atransmission portion for transmitting light from a back light in asingle display pixel, in a case where the surrounding is totally dark,as a reflection and transmission type liquid crystal display device, thedisplay is carried out by utilizing light transmitting through thetransmission portion from the back light and light reflected by thereflection portion formed by a film having comparatively highreflectance, while in a case where the surrounding is bright, as areflection type liquid crystal display device, the display is carriedout by utilizing light reflected by the reflection portion formed by thefilm having the comparatively high optical reflectance.

Further, in the above-described transflective type liquid crystaldisplay device, particularly at the reflection portion for carrying outreflection display, a special concavo-convex structure having opticaldiffusion is given. Since a reflection electrode, according to thestructure thereof, reflects light from a certain direction by a certainincident angle only to a location having a specific exit angle in aspecific direction (Snell's law) to the surface, when the surface isflat, a direction and an angle of emitting light are determined to beconstant relative to incidence of light. If a display is fabricatedunder such a state, a display having very poor visibility is broughtabout.

The liquid crystal display device of a transflective type is consideredas a display well coped with the particular service conditions for thepersonal digital assistant. Particularly, in the cellular phoneapplication, huge demand is to be prospectively expected from now on.For this reason, in order to secure stable demand or cope with hugedemand, there is an apparent need to make efforts toward the furtherreduction of cost.

However, in order to form a concavo-convex structure as noted before,there is a need for a method to provide a concavo-convex form in thelayer lower than the reflection electrode and then form thereon areflection electrode.

Meanwhile, in order to fabricate a transflective type liquid crystaldisplay device without limited to the foregoing example, patterning isrequired for forming a concavo-convex structure in one or both surfacesof a reflection electrode and a transparent electrode configuring apixel electrode or in the layer beneath the pixel electrode, thusincreasing the processes. The increase of processes would incur adisadvantageous situation, including yield reduction, prolonged processtime and increasing cost.

Accordingly, it is an object of the present invention to provide adisplay having high visibility and a transflective type liquid crystaldisplay device having a reflection electrode with a concavo-convexstructure formed without particularly increasing the processes.

SUMMARY OF THE INVENTION

In order to solve the foregoing problem, the present invention ischaracterized in that, in manufacturing a transflective liquid crystaldisplay device, a reflection electrode of a plurality of irregularlyarranged island-like patterns and a transparent electrode of transparentconductive film are layered in forming an electrode having transparentand reflection electrodes thereby providing a concavo-convex form andenhancing the scattering ability of light and hence display visibility.Furthermore, because the plurality of irregularly arranged island-likepatterns can be formed simultaneous with the interconnection, aconcavo-convex structure can be formed in the manufacturing processwithout especially increasing the patterning process only for forming aconcavo-convex structure. Accordingly, it is possible to greatly reducecost and improve productivity.

A liquid crystal display device of the invention is a liquid crystaldisplay device comprising: a transparent conductive film formed on aninsulating surface; and an interconnection and a plurality ofirregularly arranged island-like patterns that are formed on thetransparent conductive film; electrical connection being made betweenthe transparent conductive film, the interconnection and the pluralityof irregularly arranged island-like patterns.

The plurality of irregularly arranged island-like patterns serve as areflection electrode. Also, by layering the transparent electrode oftransparent conductive film and the reflection electrode of theplurality of irregularly arranged island-like patterns, the regionhaving the reflection electrode serves as an electrode having areflectivity to light. The region, not having a reflection electrode onthe transparent electrode but exposed with the transparent electrode inthe surface, serves as a transparent electrode having transmittabilityto light. Accordingly, in the invention, a transflective type liquidcrystal display device is formed which has, as a pixel electrode, anelectrode having two kinds of natures, i.e. reflectivity andtransmittability. Namely, the pixel electrode of the invention comprisesa reflection electrode and a transparent electrode, thus having aconcavo-convex structure.

Meanwhile, the reflective conductive film of the invention assumably usea conductive film having a reflectivity of 75% or higher in respect ofthe vertical reflection characteristic in a wavelength of 400–800 nm(visible light region). Incidentally, such a material can use aluminum(Al) or silver (Ag), or, besides them, an alloy material based on these.

Also, a liquid crystal display device in another structure of theinvention is a liquid crystal display device comprising: a thin-filmtransistor formed over a substrate; a transparent conductive film formedon the thin-film transistor through an insulating film; and aninterconnection and a plurality of irregularly arranged island-likepatterns that are formed on the transparent conductive film; theinterconnection electrically connecting between the thin-film transistorand the transparent conductive film.

Furthermore, a liquid crystal display device of the invention is aliquid crystal display device characterized by: having a first substratehaving a first transparent conductive film, an interconnection and aplurality of irregularly arranged island-like patterns, a secondsubstrate having a second transparent conductive film and a liquidcrystal; the interconnection and the plurality of irregularly arrangedisland-like patterns being formed on the first transparent conductivefilm; electrical connection being made between the transparentconductive film, the interconnection and the plurality of irregularlyarranged island-like patterns; a film forming surface of the firstsubstrate and a film forming surface of the second substrate beingarranged opposite to each other, and the liquid crystal being sandwichedbetween the first substrate and the second substrate.

Furthermore, a liquid crystal display device of the invention is aliquid crystal display device characterized by: having a first substratehaving a thin-film transistor, a first transparent conductive film, aninterconnection and a plurality of irregularly arranged island-likepatterns, a second substrate having a second transparent conductive filmand a liquid crystal; the interconnection and the plurality ofirregularly arranged island-like patterns being formed on the firsttransparent conductive film; the interconnection electrically connectingthe thin-film transistor, the first transparent conductive film and theplurality of irregularly arranged island-like patterns; a film formingsurface of the first substrate and a film forming surface of the secondsubstrate being arranged opposite to each other, and the liquid crystalbeing sandwiched between the first substrate and the second substrate.

Incidentally, according to each of the above structures, it is possibleto form, by etching, the plurality of irregularly arranged island-likepatterns of a reflective conductive film and the interconnection.Furthermore, in the case of simultaneously forming them by etching,because a concavo-convex structure can be configured as viewed at afilm-forming surface of the reflective conductive film, it is possibleto reduce the photolithography process used in usually forming aconcavo-convex structure. This can realize great cost reduction andimprovement in productivity.

Meanwhile, the plurality of irregularly arranged island-like patterns tobe formed in each of the above structures are formed and arranged in arandom form, and electrically connected to the first transparentconductive film. However, the island-like pattern formed by etching thereflective conductive film is desirably given a smaller taper angle at apattern end in view of improving the ability of reflection.Incidentally, the plurality of island-like patterns of the invention ischaracterized by a taper angle of 5–60 degrees at each pattern end.

Furthermore, in each of the above structures, the plurality ofisland-like patterns of reflective conductive film formed in the pixelregion is characterized to have a occupation area ratio of 50–90% of thearea of the pixel region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view explaining a device structure of a liquid crystaldisplay device of the present invention;

FIGS. 2A to 2D are views explaining a structure of a reflectionelectrode of the invention;

FIGS. 3A to 3D are views showing a manufacturing process for a liquidcrystal display device of the invention;

FIG. 4 is a view showing the manufacturing process for a liquid crystaldisplay device of the invention;

FIG. 5 is a view showing the manufacturing process for a liquid crystaldisplay device of the invention;

FIG. 6 is a view showing the manufacturing process for a liquid crystaldisplay device of the invention;

FIG. 7 is a view showing the manufacturing process for a liquid crystaldisplay device of the invention;

FIGS. 8A to 8D are views showing the manufacturing process for a liquidcrystal display device of the invention;

FIG. 9 is a view showing the manufacturing process for a liquid crystaldisplay device of the invention;

FIG. 10 is a view showing the manufacturing process for a liquid crystaldisplay device of the invention;

FIG. 11 is a view explaining a structure of a liquid crystal displaydevice of the invention;

FIG. 12 is a view explaining a device structure of the liquid crystaldisplay device of the invention;

FIG. 13 is a diagram explaining a circuit configuration usable in theinvention;

FIG. 14 is a diagram explaining a circuit configuration usable in theinvention;

FIG. 15 is a view explaining an exterior appearance of the liquidcrystal display device of the invention; and

FIGS. 16A to 16F are views showing an example of electrical apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be explained withreference to FIG. 1. A semiconductor layer 105 is formed over asubstrate 101. The semiconductor layer 105 is formed, of polycrystalsemiconductor that an amorphous semiconductor has been crystallized by athermal process, having a thickness of approximately 30–750 nm, on whicha gate insulating film 106 is formed furthermore. The gate insulatingfilm 106 is formed of silicon oxide having 30–100 nm. Also, although thepolycrystal semiconductor is used as the semiconductor layer 105, anamorphous semiconductor also can be used as the semiconductor layer 105.

A gate electrode 107 and a capacitance interconnection 108 are formed ina same layer on the gate insulating film 106, on which a firstinsulating film 109 of silicon oxide and a second insulating film 110 ofacryl are formed. The material for forming a first insulating film 109can use, besides silicon oxide, a silicon-contained inorganic material,such as silicon nitride, silicon nitride oxide or applied silicon oxide(SOG: Spin On Glass). The material for forming a second insulating film110 can use, besides acryl (including photosensitive acryl), an organicmaterial, such as polyimide, polyamide, BCB (benzocyclo-butene).

A transparent electrode 111 is an electrode for allowing incident lightto transmit toward the substrate 101. The transparent electrode 111 isformed in a film thickness of 100–200 nm by using, as a material, atransparent conductive film of indium oxide-tin (ITO) or indium oxidemixed with zinc oxide (ZnO) in 2–20[%]. This is further patterned toform transparent electrodes 111 on a pixel-by-pixel basis.

An interconnection 112 is an electrode forming a contact to a sourceregion 102 of a TFT 115, also serving as a source line. Theinterconnection 113 is an electrode forming a contact to a drain regionof the TFT 115.

The semiconductor layer 105 is formed with a source region 102, a drainregion 103 and a channel region 104. Except the source region 102 anddrain region 103, the semiconductor layer 105 formed in a regionoverlapped with a capacitance interconnection 108 serves as oneelectrode of a capacitance element.

Meanwhile, on the transparent electrode 111 formed before, a reflectionelectrode 114 is formed by a reflection conductive film in the same filmas the conductive film forming the interconnections 112, 113. Namely, aphotolithography technique is used to form a plurality of island-likepatterns on the transparent electrode 111 in the pixel region. In theregion other than those, interconnections 112, 113 are formed. Theisland-like patterns herein are in a random form and arrangement formingthe reflecting electrode 114. The reflection electrode 114 thusstructured can possess a function to scatter the incident light on thesurface.

According to the structure of the invention, the light, incident on thereflection electrode 114 formed on the transparent electrode 111, iscause to scatter by the form of the reflection electrode 114. However,the light incident on a region, exposed with the transparent electrode222 instead of forming the reflection electrode 114, transmits throughthe transparent electrode 111 and exits toward the substrate 101.

The reflection electrode formed in the invention, formed in a randomform and region as shown in its form in FIG. 2A, can cause deviationbetween the angle of an incident light on the reflection electrode(incident angle) and the angle of a light reflected upon the reflectionelectrode (reflection angle) thereby scattering the light.

Incidentally, in the invention, importance is placed on the form of aplurality of reflectors configuring the reflection electrode in respectof causing deviation between the incident angle and the reflectionangle, i.e. an angle representative of in what degree the taper slopesurface (reflection surface) 210 of each reflector shown in FIG. 2Binclines with respect to a substrate surface (reference surface) 211.This is shown as a taper angle (θ) 212.

In this embodiment, the reflectors are formed with a taper angle (θ) 212of 5–60 degrees. Due to this, the exit angle with respect to the taperslope surface (reflection surface) 211 is deviated as compared to theexit angle with respect to the substrate surface (reference surface) 210to cause light scattering. This makes it possible to improve visibility.

FIG. 2C shows a behavior of incident light 213 and reflection light 214upon a reflection surface not sloped. It is assumed that an incidentdirection on the reference surface 211 is a_(in), an exit direction isa_(out), an incident direction on the reflection surface 210 is a′_(in),and an exit direction is a′_(out). Furthermore, an incident angle (φ₁))215 and an exit angle (φ₂) 216 are defined with respect to the referencesurface. Herein, since there is coincidence between the referencesurface 211 and the reflection surface 210, a_(in)=a′_(in)=φ₁ anda_(out)=a′_(out)=φ₂ are held.

Also, from a′_(in)=a′_(out) held on the Snell's law, a_(in)=a_(out) andφ₁=φ₂ are held.

On the other hand, FIG. 2D shows a behavior of incident light 213 andexit light 214 in the case the taper slope surface having a taper angle(θ) 212 is made as a reflection surface.

Provided that the incident light 213 and the exit light 214 arerespectively an incident angle (φ₁′) 217 and an exit angle (φ₂′) 218with respect to the reference surface 211, then a_(in)=φ₁′ anda_(out)=φ₂′ and further a′_(in)=φ₁′=θ and a′_(out)=φ₂′−θ are held.

Meanwhile, because a′_(in)=a′_(out) is held on the Snell's law,φ₁′+θ=φ₂′−θ is held. From this equation, the relationship between anincident angle (φ₁′) 217 and an exit angle (φ₂′) 218 can be expressed byφ₂′−φ₁′=2θ. This means that there is a deviation by 2θ between theincident direction (a_(in)) of incident light 213 and the exit direction(a_(out)) of exit light 214.

In order to fabricate a panel further excellent in visibility, it ispreferred to evenly distribute the relevant deviation angle (2θ) withina range of 40 degrees or smaller. Consequently, the reflectors 204 arefurther, preferably formed to provide a taper angle (θ) 212 of 20degrees or smaller.

In this embodiment, by forming the reflectors 204 structuring areflection electrode 114 with a taper angle (θ) 212 of 5–60 degrees, thelight incident on the reflection electrode 114 can be scatteredefficiently. Accordingly, the structure of the invention makes itpossible to enhance display visibility without increasing themanufacture processes for TFTs.

Incidentally, a transflective type liquid crystal display device can beformed by mating a counter substrate (not shown) having a counterelectrode on a device substrate (FIG. 1) having TFTs on the substrateexplained in the embodiment and then providing a liquid crystal betweenthe both.

EXAMPLES

Examples of the invention will be explained as follows.

Example 1

According to the example, an example of steps of fabricating an activematrix substrate having a top gate type TFT will be shown. Further, FIG.3A through FIG. 7 showing top views and sectional views of a portion ofa pixel portion will be used for explanation.

First, an amorphous semiconductor layer is formed over a substrate 301having an insulating surface. Here, a quartz substrate is used as thesubstrate 301 and the amorphous semiconductor layer is formed with athickness of 10 through 100 nm.

Further, a glass substrate or a plastic substrate can be used other thanthe quartz substrate. When the glass substrate is used, the glasssubstrate may be subjected to a heat treatment previously at atemperature lower than a glass strain point by about 10 through 20° C.Further, a base film comprising an insulating film such as a siliconoxide film, a silicon nitride film, a silicon oxynitride film and thelike may be formed on a surface of the substrate 301 for forming TFT toprevent an impurity from diffusing from the substrate 301.

As the amorphous semiconductor layer, an amorphous silicon film(amorphous silicon film) having a film thickness of 60 nm is formed byLPCVD method. Successively, the amorphous semiconductor layer iscrystallized. Here, the amorphous semiconductor layer is crystallized byusing a technology described in JP-A-8-78329. According to thetechnology described in the publication, an amorphous silicon film isselectively added with a metal element to help the crystallization ofthe amorphous silicon film and a heating treatment is carried out tothereby form a crystalline silicon film spreading with an additionregion as a start point. Here, nickel is used as a metal element forhelping the crystallization and after a heat treatment fordehydrogenation (450° C., 1 hour), a heat treatment for crystallization(600° C., 12 hours) is carried out. Further, although the technologydescribed in the publication is used here for the crystallization, theinvention is not particularly limited to the technology but a publiclyknown crystallizing processing (laser crystallizing method, thermalcrystallizing method) can be used.

Further, as necessary, a laser beam (XeCl: wavelength 308 nm) isirradiated in order to increase a crystallization rate and repairing adefect that remains in a crystal grain. As the laser beam, an excimerlaser beam, or a second harmonic or third harmonic of YAG laser having awavelength equal to or smaller than 400 nm is used. At any rate, a pulselaser beam having a repeating frequency of about 10 through 1000 Hz maybe used and the laser beam may be focused to 100 through 400 mJ/cm² byan optical system, irradiated by 90 through 95% of an overlap rate andscanned on a surface of a silicon film.

Successively, Ni is gettered from a region constituting an active layerof TFT. Here, as a gettering method, an example of using a semiconductorlayer including a rare gas element will be shown. In addition to anoxide film formed by irradiating the laser beam, a barrier layercomprising an oxide film of a total of 1 through 5 nm is formed byprocessing a surface for 120 seconds by ozone water. Successively, anamorphous silicon film including argon element constituting a getteringsite is formed on the barrier layer by a sputtering method with a filmthickness of 150 nm. According to film forming conditions by thesputtering method of the example, film forming pressure is set to 0.3Pa, a flow rate of gas (Ar) is set to 50 (sccm), film forming power isset to 3 kW and substrate temperature is set to 150° C. Further, atomicconcentration of argon element included in the amorphous silicon filmfalls in a range of 3×10²⁰/cm³ through 6×10²⁰/cm³ and atomicconcentration of oxygen falls in a range of 1×10¹⁹/cm³ through3×10¹⁹/cm³ under the above-described conditions. Thereafter, getteringis carried out by a heat treatment at 650° C. for 3 minutes by using alamp annealing device. Further, an electric furnace may be used in placeof the lamp annealing device.

Successively, by constituting an etching stopper by the barrier layer,the amorphous silicon film including argon element constituting thegettering side is selectively removed and thereafter, the barrier layeris selectively removed by diluted hydrofluoric acid. Further, ingettering, since nickel tends to move to a region having a high oxygenconcentration, a barrier layer comprising an oxide film may preferablybe removed after gettering.

After forming a thin oxide film on a surface of a silicon film (alsoreferred to as polysilicon film) having the provided crystallinestructure by ozone water, a mask comprising a resist is formed, thesilicon film is etched to a desired shape and a semiconductor layer 305separated in an island-like shape is formed. After forming thesemiconductor layer 305, the mask comprising the resist is removed, agate insulating film 306 covering the semiconductor layer 305 is formedwith a film thickness of 100 nm and thereafter, thermal oxidation iscarried out.

Successively, a channel doping step of adding a P-type or an N-typeimpurity element to a region for constituting a channel region of TFT ata low concentration is carried out over an entire face thereof orselectively. The channel doping step is a step of controlling thresholdvoltage of TFT. Further, as an impurity element for providing P-type toa semiconductor, elements of 13-th group of the periodic law such asboron (B), aluminum (Al) or gallium (Ga) are known. Further, as impurityelements for providing n-type to a semiconductor, elements belonging to15-th group of the periodic law, typically, phosphor (P) and arsenic(As) are known. Further, here, boron is added by a plasma-exciting iondoping method without subjecting dibolane (B₂H₆) to mass separation.Naturally, an ion implantation method for carrying out mass separationmay be used.

Successively, a first conductive film is formed and patterned to therebyform a gate electrode 307 and a capacitance interconnection 308. Alaminated structure of tantalum nitride (TaN) (film thickness 30 nm) andtungsten (film thickness 370 nm) is used. Here, a double gate structureis constituted in the example. Further, holding capacitance isconstituted by the capacitance interconnection 308 and a region a (303a) constituting a portion of the semiconductor layer 305 with the gateinsulating film 306 being as a dielectric.

Then, phosphorus is added at low concentration through the gateelectrode 307 and capacitance interconnection 308 as a mask in aself-aligned manner. In the region added at low concentration,phosphorus concentration is controlled to 1×10¹⁶−5×10¹⁸/cm³, typically3×10¹⁷−3×10¹⁸/cm³.

Next, a mask (not shown) is formed to add phosphorus at highconcentration to form a high-concentration impurity region to be madeinto a source region 302 or drain region 303. In this high-concentrationimpurity region, phosphorus concentration is controlled to1×10²⁰−1×10²¹/cm³ (typically 2×10²⁰−5×10²⁰/cm³). The semiconductor layer305, in a region overlapped with the gate electrode 307, is formed intoa channel region 304. The region covered by the mask is formed into alow-concentration impurity region and into an LDD region 311.Furthermore, a region not covered by any of the gate electrode 307, thecapacitance line 308 and the mask is made as a high-concentrationimpurity region including a source region 302 and a drain region 303.

Further, according to the example, TFTs of the pixel portion and TFTs ofa drive circuit are formed on the same substrate and in the TFTs of thedrive circuit, a low concentration impurity region having an impurityconcentration lower than those of source and drain regions may beprovided between a source and a drain region on both sides of a channelformation region or the low concentration impurity region may beprovided on one side thereof. However, it is not always necessarily toprovide the low concentration impurity region on the both sides, aperson carrying out the example may design a mask appropriately.

In addition, although not illustrated here, because this example formsp-channel TFTs to be used for a drive circuit formed on the samesubstrate as the pixels, the region to be formed into n-channel TFTs iscovered by a mask to add boron thereby forming a source or drain region.

Then, after removing the mask, a first insulating film 309 is formedcovering the gate electrode 307, the capacitance interconnection 308.Herein, a silicon oxide film is formed in a film thickness of 50 nm, anda thermal process is carried out to activate the n-type or p-typeimpurity element added at respective concentrations in the semiconductorlayer 305. Herein, thermal process is made at 850° C. for 30 minutes(FIG. 3A). Incidentally, a pixel top view herein is shown in FIG. 4. InFIG. 4, the sectional view taken along the dotted line A-A′ correspondsto FIG. 3A.

Then, after carrying out a hydrogenation process, a second insulatingfilm 313 is formed of an organic resin material. By herein using anacryl film having a film thickness of 1 μm, the second insulating film313 can be flattened in its surface. This prevents the affection of astep caused by the pattern formed in the layer beneath the secondinsulating film 313. Then, a mask is formed on the second insulatingfilm 313, to form by etching a contact hole 312 reaching thesemiconductor layer 305 (FIG. 3B). After forming the contact hole 312,the mask is removed away. Further, FIG. 5 shows a top view of the pixelin this case. In FIG. 5, a sectional view taken along the dotted lineA–A′ corresponds to FIG. 3B.

Next, a 120-nm transparent conductive film (herein, indium oxide-tin(ITO) film) is deposited by sputtering, and patterned into a rectangularform by the use of a photolithography technique. After carrying out awet-etching treatment, a heating treatment is made in a clean oven at250° C. for 60 minutes thereby forming a transparent electrode 313 (FIG.3C). The pixel top view herein is shown in FIG. 6. In FIG. 6, thesectional view taken along the dotted line A-A′ corresponds to FIG. 3C.

Next, a second conductive film is formed and patterned. Due to this,formed are, besides a reflection electrode 314 formed on the transparentelectrode 313, an interconnection 315 which is also a source line and anintersection 316 electrically connecting between a TFT 310 and thetransparent electrode 313 are formed. Note that the second conductivefilm formed herein is a reflective conductive film to form a reflectionelectrode of the invention, which can use aluminum or silver, orotherwise an alloy material based on these.

This example uses a layered film having a two-layer structurecontinuously formed, by a sputter method, with a Ti film having 50 nm asthe second conductive film and an Si-contained aluminum film having 500nm.

The method of patterning uses a photolithography technique to form areflection electrode 314 comprising a plurality of island-like patternsand interconnections 315, 316. The method for etching herein uses a dryetching scheme to carry out taper etching and anisotropic etching.

At first, a resist mask is formed to carry out a first etching processfor taper etching. The first etching process is under first and secondetching conditions. For etching, an ICP (Inductively Coupled Plasma)etching technique is suitably used. Using the ICP etching technique, thefilm can be etched to a desired taper form by properly controlling theetching condition (amount of power applied to a coil-formed electrode,amount of power applied to a substrate-sided electrode, electrodetemperature close to the substrate, etc.). The etching gas can suitablyuse a chlorine-based gas represented by Cl₂, BCl₃, SiCl₄, CCl₄ or thelike, a fluorine-based gas represented by CF₄, SF₆, NF₃ or the like, orO₂.

This example uses the ICP (Inductively Coupled Plasma) etchingtechnique, as a first etching condition, wherein BCl₃, Cl₂ and O₂ areused for an etching gas. Etching is conducted with plasma caused byfeeding a 500 W RF (13.56 MHz) power to a coil-formed electrode at aflow rate ratio of these gasses of 65/10/5 (sccm) under a pressure of1.2 Pa. A 300 W RF (13.56 MHz) power is fed also to the substrate side(sample stage) to apply substantially a negative self-bias voltage.Under the first etching condition, the Si-contained aluminum film isetched to make the first conductive layer at its end into a taper form.

Thereafter, the second etching condition is changed without removing themask. Using CF₄, Cl₂ and O₂ for an etching gas, etching is conducted fornearly 30 seconds with plasma caused by feeding a 500 W RF (13.56 MHz)power to the coil-formed electrode at a flow rate ratio of these gassesof 25/25/10 (sccm) under a pressure of 1 Pa. A 20 W RF (13.56 MHz) poweris fed also to the substrate side (sample stage) to apply substantiallya negative self-bias voltage. Under the second etching condition havingCF₄ and Cl₂ mixed together, the Si-contained aluminum film and the Tifilm are both etched in the same degree.

In this manner, by the first etching process, the second conductive filmcomprising the first and second conductive layers can be made into ataper form.

Then, a second etching process for anisotropic etching is carried outwithout removing the resist mask. Using herein BCl₃ and Cl₂ for anetching gas, etching is conducted with plasma caused by feeding a 300 WRF (13.56 MHz) power to the coil-formed electrode at a flow rate ratioof these gasses of 80/20 (sccm) under a pressure of 1 Pa. A 50 W RF(13.56 MHz) power is fed also to the substrate side (sample stage) toapply substantially a negative self-bias voltage.

By the above, at a time that a reflection electrode 314 andinterconnections 315 and 316 are formed, the resist is removed to obtaina structure shown in FIG. 3D. Incidentally, a pixel top view herein isshown in FIG. 7. In FIG. 7, the sectional view taken along the dottedline A–A′ corresponds to FIG. 3D.

Further, by randomly forming the reflecting electrode 314 above thetransparent electrode 313 as shown in FIG. 7, at portions of thetransparent electrode 313 and the reflecting electrode 314 formed tooverlap, light is reflected by the reflecting electrode 314 and at aportion at which the reflecting electrode 314 is not formed and thetransparent electrode 313 is exposed to the surface, light transmitsthrough an inner portion of the transparent electrode 313 and is emittedto a side of the substrate 301.

In this way, the pixel portion having the n-channel type TFT having thedouble gate structure and the holding capacitance and the drive circuithaving the n-channel type TFT and the p-channel type TFT can be formedon the same substrate. In the specification, such a substrate isreferred to as an active matrix substrate for convenience.

Further, the example is only an example, needless to say the inventionis not limited to steps of the example. For example, as respectiveconductive films, a film of an element selected from the groupconstituting of tantalum (Ta), titanium (Ti), molybdenum (Mo), tungsten(W), chromium (Cr) and silicon (Si) or an alloy combined with theelements (representatively, Mo—W alloy, Mo—Ta alloy) can be used.Further, as the respective insulating films, a silicon oxide film, asilicon nitride film, a silicon oxynitride film, a film of an organicresin material (polyimide, acrylic resin, polyamide, polyimideamide, BCB(benzocyclobutene) etc) can be used.

Meanwhile, according to the process shown in this example, it ispossible to simultaneously form a reflection electrode 314 andinterconnections 315 and 316 by using a interconnection pattern mask asshown in FIG. 3D. Consequently, the reflection electrode can be formedseparately in plurality in an island form on a transparent electrodewithout increasing the number of photo-masks required in fabricating anactive matrix substrate. As a result, in the manufacture of atransflective type liquid crystal display device, the process can beshortened thereby giving contribution to manufacture cost reduction andyield improvement.

Example 2

This example concretely explains a method for manufacturing atransflective type liquid crystal display device different in structurefrom Example 1.

At first, an amorphous semiconductor film is formed over a substrate 801as shown in FIG. 8A. After crystallizing this, a semiconductor layer 805is formed which is separated in an island form by patterning.Furthermore, on the semiconductor layer 805, a gate insulating film 806is formed by an insulating film. Incidentally, the manufacturing methodof up to forming a gate insulating film 806 is similar to that shown inExample 1, and hence reference may be made to Example 1. Similarly,after forming an insulating film covering the semiconductor layer 805,thermal oxidation is carried out to form a gate insulating film 806.

Then, a channel dope process is carried out over the entire surface orselectively, to add a p-type or n-type impurity element at lowconcentration to a region to be made into a TFT channel region.

A conductive film is formed on the gate insulating film 806. Bypatterning this, an interconnection 809 can be formed that is to be madeinto a gate electrode 807, a capacitance interconnection 808 and asource line. Incidentally, the first conductive film in this example isformed by layering TaN (tantalum nitride) formed in a thickness of50–100 nm and W (tungsten) formed in a thickness of 100–400 nm.

Although this example formed the conductive film by the use of thelayers of TaN and W, they are not especially limited, i.e. both may beformed of an element selected from Ta, W, Ti, Mo, Al and Cu or an alloyor compound material based on the element. Otherwise, a semiconductorfilm may be used that is represented by a polycrystal silicon film dopedwith an impurity element, such as phosphorus.

Then, phosphorus is added at low concentration through the gateelectrode 807 and capacitance interconnection 808 as a mask in aself-aligned fashion. In the region added at low concentration,phosphorus concentration is controlled to 1×10¹⁶−5×10¹⁸/cm³, typically3×10¹⁷−3×10¹⁸/cm³.

Next, a mask (not shown) is formed to add phosphorus at highconcentration to form a high-concentration impurity region to be madeinto a source region 802 or drain region 803. In this high-concentrationimpurity region, phosphorus concentration is controlled to1×10²⁰−1×10²¹/cm³ (typically 2×10²⁰−5×10²⁰/cm³). The semiconductor layer805, in a region overlapped with the gate electrode 807, is formed intoa channel region 804. The region covered by the mask is formed into alow-concentration impurity region and into an LDD region 811.Furthermore, the region not covered by any of the gate electrode 807,the capacitance line 808 and the mask is made as a high-concentrationimpurity region including a source region 802 and a drain region 803.

Meanwhile, because this example forms p-channel TFTs to be used for adrive circuit formed on the same substrate as the pixels similarly toExample 1, the region to be formed into n-channel TFTs is covered by amask to add boron thereby forming a source or drain region.

Then, after removing the mask, a first insulating film 810 is formedcovering the gate electrode 807, the capacitance interconnection 808 andinterconnection (source line) 809. Herein, a silicon oxide film isformed in a film thickness of 50 nm, and a thermal process is carriedout to activate the n-type or p-type impurity element added atrespective concentrations in the semiconductor layer 805. Herein,thermal process is made at 850° C. for 30 minutes (FIG. 8A).Incidentally, a pixel top view herein is shown in FIG. 9. In FIG. 9, thesectional view taken along the dotted line A–A′ corresponds to FIG. 8A.

Then, after carrying out a hydrogenation process, a second insulatingfilm 811 is formed of an organic resin material. By herein using anacryl film having a film thickness of 1 μm, the second insulating film811 can be flattened in its surface. This prevents the affection of astep caused by the pattern formed in the layer beneath the secondinsulating film 811. Then, a mask is formed on the second insulatingfilm 811, to form by etching a contact hole 812 reaching thesemiconductor layer 805 (FIG. 8B). After forming the contact hole 812,the mask is removed away.

Next, a 120-nm transparent conductive film (herein, indium oxide-tin(ITO) film) is deposited by sputtering, and patterned into a rectangularform by the use of a photolithography technique. After carrying out awet-etching treatment, heating treatment is made in a clean oven at 250°C. for 60 minutes thereby forming a transparent electrode 813 (FIG. 8C).The pixel top view herein is shown in FIG. 9. In FIG. 9, the sectionalview taken along the dotted line A–A′ corresponds to FIG. 8C.

Next, a second conductive film is formed and patterned. Due to this,formed are, besides a reflection electrode 814 formed on the transparentelectrode 813, an interconnection 815 electrically connecting betweenthe interconnection (source line) 809 and the source region of TFT 820,an interconnection 816 forming a contact with the drain region of TFT820, and an interconnection 817 electrically connecting between thedrain region of TFT 820 and the transparent electrode 813. The secondconductive film formed herein is a reflective conductive film to form areflection electrode of the invention, which can use aluminum or silver,or otherwise an alloy material based on these.

This example uses a layered film having a two-layer structurecontinuously formed, by a sputter method, with a Ti film having 50 nm asthe second conductive film and a Si-contained aluminum film having 500nm.

The method of patterning uses a photolithography technique to form areflection electrode 814 comprising a plurality of island-like patternsand interconnections 815, 816, 817. The method for etching herein uses adry etching scheme to carry out taper etching and anisotropic etching.

At first, a resist mask is formed to carry out a first etching processfor taper etching. The first etching process is under first and secondetching conditions. For etching, an ICP (Inductively Coupled Plasma)etching technique is suitably used. Using the ICP etching technique, thefilm can be etched to a desired taper form by properly controlling theetching condition (amount of power applied to a coil-formed electrode,amount of power applied to a substrate-sided electrode, electrodetemperature close to the substrate, etc.). The etching gas can suitablyuse a chlorine-based gas represented by Cl₂, BCl₃, SiCl₄, CCl₄ or thelike, a fluorine-based gas represented by CF₄, SF₆, NF₃ or the like, orO₂.

This example uses the ICP (Inductively Coupled Plasma) etchingtechnique, as a first etching condition, wherein BCl₃, Cl₂ and O₂ areused for an etching gas. Etching is conducted with a plasma caused byfeeding a 500 W RF (13.56 MHz) power to a coil-formed electrode at aflow rate ratio of these gasses of 65/10/5 (sccm) under a pressure of1.2 Pa. A 300 W RF (13.56 MHz) power is fed also to the substrate side(sample stage) to apply substantially a negative self-bias voltage.Under the first etching condition, the Si-contained aluminum film isetched to make the first conductive layer at its end into a taper form.

Thereafter, the mask is not removed for change to the second etchingcondition. Using CF₄, Cl₂ and O₂ for an etching gas, etching isconducted for nearly 30 seconds with a plasma caused by feeding a 500 WRF (13.56 MHz) power to the coil-formed electrode at a flow rate ratioof these gasses of 25/25/10 (sccm) under a pressure of 1.2 Pa. A 20 W RF(13.56 MHz) power is fed also to the substrate side (sample stage) toapply substantially a negative self-bias voltage. Under the secondetching condition having CF₄ and Cl₂ mixed together, the Si-containedaluminum film and the Ti film are both etched in the same degree.

In this manner, by the first etching process, the second conductive filmcomprising the first and second conductive layers can be made into ataper form.

Then, the resist mask is not removed to carry out a second etchingprocess for anisotropic etching. Using herein BCl₃ and Cl₂ for anetching gas, etching is conducted with a plasma caused by feeding a 300W RF (13.56 MHz) power to the coil-formed electrode at a flow rate ratioof these gasses of 80/20 (sccm) under a pressure of 1 Pa. A 50 W RF(13.56 MHz) power is fed also to the substrate side (sample stage) toapply substantially a negative self-bias voltage.

By the above, at a time that a reflection electrode 814 andinterconnections 815, 816 and 817 are formed, the resist is removed toobtain a structure shown in FIG. 8D. Incidentally, a pixel top viewherein is shown in FIG. 10. In FIG. 10, the sectional view taken alongthe dotted line A–A′ corresponds to FIG. 8D.

In the above manner, this example also forms an active matrix substratehaving, on the same substrate, a pixel region havingdouble-gate-structured n-channel TFTs and holding capacitances and adrive circuit having n-channel and p-channel TFTs.

Meanwhile, according to the process shown in this example, it ispossible to simultaneously form a reflection electrode 814, andinterconnections 815 816 and 817 by using a interconnection pattern maskas shown in FIG. 8D. Consequently, the reflection electrode can beformed separately in plurality in an island form on a transparentelectrode without increasing the number of photo-masks required infabricating an active matrix substrate. As a result, in the manufactureof a transflective liquid crystal display device, the process can beshortened thereby giving contribution to manufacture cost reduction andyield improvement.

Example 3

This example explains a method for manufacturing an active matrixsubstrate different in structure from the one showing in Examples 1 and2.

In FIG. 12, over a substrate 1201 is formed a TFT 1215 having a gateelectrode 1207, a source region 1202, a drain region 1203 andinterconnections 1212 and 1213. The interconnections 1212 and 1213 arerespectively, electrically connected to the source region and the drainregion.

Incidentally, the active matrix substrate of this example is differentfrom Examples 1 and 2 in that a transparent electrode 1211 is formedafter forming the interconnections 1212 and 1213.

Similarly to the one showing in Example 1 or 2, a second insulating film1210 is formed and, after a contact hole is formed therein, a secondconductive film is formed. The material of the second conductive filmused herein can use the same material as that of Example 1 or 2.

By patterning the second conductive film, it is possible to forminterconnections 1212 and 1213 and a reflection electrode 1214.Incidentally, a reflection electrode 1214 having a plurality ofisland-like patterns can be formed by a method similar to the method forforming the reflection film formed in Example 1 or 2. However, becausethe reflection electrode 1214 of this example is formed separately in anisland form on the second insulating film 1210, during formation it isnot electrically connected to the TFT 1215. Thereafter, an electricalconnection can be formed by forming the layer of a transparentconductive film 1211 on part of the interconnection 1213 and on thereflection electrode 1214.

Incidentally, the active-matrix substrate fabricated in this example canbe manufactured as a liquid crystal display device by implementing themethod shown in

Example 4

According to the example, steps of fabricating a transflective typeliquid crystal display device from the active matrix substratefabricated by Example 1 will be explained as follows. A sectional viewof FIG. 11 is used for explanation.

First, after obtaining the active matrix substrate of FIG. 3D inaccordance with the example 1, as shown by FIG. 11, an alignment film1119 is formed on the active matrix substrate and rubbing treatment iscarried out. Further, according to the example, after forming thealignment film 1119, spherical spacers 1121 for holding an intervalbetween the substrates are scattered over entire surfaces of thesubstrates. Further, in place of the spherical spacers 1121, column-likespacers may be formed at desired positions by patterning an organicresin film of an acrylic resin film or the like.

Next, a substrate 1122 is prepared. A coloring layer 1123 (1123 a, 1123b) and a flattening layer 1124 are formed on the substrate 1122.Further, as the coloring layer 1123, a coloring layer 1123 a of redcolor, a coloring layer 1123 b of blue color and a coloring layer ofgreen color (not illustrated) are formed. Further, although notillustrated here, a light blocking portion may be formed by partiallyoverlapping the coloring layer 1123 a of the red color and the coloringlayer 1123 b of the blue color or partially overlapping the coloringlayer 1123 a of the red color and the coloring layer of the green color(not illustrated).

Further, an opposed electrode 1125 comprising a transparent conductivefilm is formed on the flattening film 1124 at a position forconstituting a pixel portion, an alignment film 1126 is formed over anentire face of the substrate 1122 and rubbing treatment is carried outto thereby provide an opposed substrate 1128.

Further, the active matrix substrate formed with the alignment film 1119on the surface and the opposed substrate 1128 are pasted together by aseal agent (not illustrated). The seal agent is mixed with a filler andtwo sheets of the substrates are pasted together with a uniform interval(preferably, 2.0 through 3.0 μm) therebetween by the filler and thespherical spacers. Thereafter, a liquid crystal material 1127 isinjected between the two substrates and completely sealed by a sealagent (not illustrated). A publicly known liquid crystal material may beused for the liquid crystal material 1127. In this way, thetransflective type liquid crystal display device shown in FIG. 11 isfinished. Further, as necessary, the active matrix substrate or theopposed substrate 1128 is divided to cut in a desired shape. Further,polarizers and the like are pertinently provided by using a publiclyknown technology. Further, FPC is pasted thereto by using the publiclyknown technology.

The constitution of the liquid crystal module provided in this way willbe explained in reference to a top view of FIG. 15. A pixel portion 1504is arranged at the center of an active matrix substrate 1501. A sourcesignal line drive circuit 1502 for driving a source signal line isarranged on an upper side of the pixel portions 1504. Gate signal linedrive circuits 1503 for driving gate signal lines are arranged on theleft and on the right of the pixel portion 1504. Although according toan example shown by the example, the gate signal line drive circuits1503 are symmetrically arranged on the left and on the right of thepixel portion, the gate signal line drive circuit 1503 may be arrangedto only one side thereof and a designer may pertinently select the sidein consideration of a substrate size of the liquid crystal module or thelike. However, the left and right symmetric arrangement shown in FIG. 15is preferable in consideration of operational reliability and driveefficiency of circuit.

Signals are inputted to respective drive circuits from flexible printcircuits (FPC) 1505. According to FPC 1505, after opening contact holesat an interlayer insulating film and a resin film to reach ainterconnection arranged at a predetermined location of the substrate1501 and forming a connection electrode (not illustrated), FPC 1505 ispressed thereto via an anisotropic conductive film or the like.According to the example, the connection electrode is formed by usingITO.

At surroundings of the drive circuit and the pixel portion, a seal agent1507 is coated along the outer periphery of the substrate and an opposedsubstrate 1506 is pasted in a state of maintaining a constant gap(interval between the substrate 1501 and the opposed substrate 1506) byspacers previously formed on the active matrix substrate. Thereafter,liquid crystal elements are injected from portions at which the sealagent 1507 is not coated and the substrates are hermetically sealed by aseal agent 1508. The liquid crystal module is finished by theabove-described steps. Further, although an example of forming all thedrive circuits on the substrates is shown here, several pieces of ICsmay be used at portions of the drive circuit. Thereby, the active matrixtype liquid crystal display device is finished.

Example 5

FIGS. 13 and 14 show block diagrams of an electro-optic devicemanufactured in accordance with the present invention. Note that FIG. 13shows the structure of a circuit used for performing analog driving.This example describes an electro-optic device having a source sidedriver circuit 90, a pixel portion 91, and a gate side driver circuit92. The term driver circuit herein collectively refers to a source sidedriver circuit and a gate side driver circuit.

The source side driver circuit 90 is provided with a shift register 90a, a buffer 90 b, and a sampling circuit (transfer gate) 90 c. The gateside driver circuit 92 is provided with a shift register 92 a, a levelshifter 92 b, and a buffer 92 c. If necessary, a level shifter circuitmay be provided between the sampling circuit and the shift register.

In this example, the pixel portion 91 is composed of a plurality ofpixels, and each of the plural pixels has TFT elements.

Though not shown in the drawing, another gate side driver circuit may beprovided in across the pixel portion 91 from the gate side drivercircuit 92.

When the device is digitally driven, the sampling circuit is replaced bya latch (A) 93 b and a latch (B) 93 c as shown in FIG. 14. A source sidedriver circuit 93 is provided with a shift register 93 a, the latch (A)93 b, the latch (B) 93 c, a D/A converter 93 d, and a buffer 93 e. Agate side driver circuit 95 is provided with a shift register 95 a, alevel shifter 95 b, and a buffer 95 c. If necessary, a level shiftercircuit may be provided between the latch (B) 93 c and the D/A converter93 d.

The above structure is obtained by employing the manufacture process ofeither Example 1 or 2. Although this example describes only thestructure of the pixel portion and the driver circuit, a memory circuitand a microprocessor circuit can also be formed when following themanufacture process of the present invention.

Example 6

The transflective type liquid crystal display device fabricated bycarrying out the invention can be used in various electro-optic devices.Further, the invention is applicable to all electronic apparatusintegrated with the electro-optic devices as display media.

As electronic apparatus fabricated by using the liquid crystal displaydevice fabricated according to the invention, there are pointed out avideo camera, a digital camera, a navigation system, a voice reproducingdevice (car audio, audio component), a notebook type personal computer,a game machine, a portable information terminal (mobile computer,cellular phone, portable game machine or electronic book), devicereproducing record media of image reproducing device having record media(specifically, digital video disk (DVD)) and having display devicescapable of displaying the image. FIGS. 16A to 16F show specific examplesof the electronic apparatus.

FIG. 16A is a digital still camera which includes a main body 2101, adisplay portion 2102, an image receiving portion 2103, an operation key2104 and an outside connection port 2105 and a shutter 2106. The digitalstill camera is fabricated by using the liquid crystal display devicefabricated by the invention at the display portion 2102.

FIG. 16B is a notebook type personal computer which includes a main body2201, a cabinet 2202, a display portion 2203, a keyboard 2204, anoutside connection port 2205 and a pointing mouse 2206. The notebooktype personal computer is fabricated by using the liquid crystal displaydevice fabricated by the invention at the display portion 2203.

FIG. 16C shows a mobile computer which includes a main body 2301, adisplay portion 2302, a switch 2303, an operation key 2304 and aninfrared ray port 2305. The mobile computer is fabricated by using theliquid crystal display device fabricated by the invention at the displayportion 2302.

FIG. 16D shows a portable image reproducing device having a recordmedium (specifically, DVD reproducing device) which includes a main body2401, a cabinet 2402, a display portion A 2403, a display portion B2404, a record medium (DVD etc) reading portion 2405, an operation key2406, and a speaker portion 2407. The display portion A 2403 mainlydisplays image information, the display portion B 2404 mainly displayscharacter information and the portable image reproducing device isfabricated by using the liquid crystal display device fabricated by theinvention at the display portions A, B 2403, 2404. Further, the imagereproducing device having the record media includes a game machine forhousehold use.

FIG. 16E shows a video camera which includes a main body 2601, a displayportion 2602, a cabinet 2603, an outside connection port 2604, a remotecontrol receiving portion 2605, an image receiving portion 2606, abattery 2607, a voice input portion 2608, an operation key 2609 and aneye-piece portion 2610. The video camera is fabricated by using theliquid crystal display device fabricated by the invention at the displayportion 2602.

Here, FIG. 16F shows a cellular phone which includes a main body portion2701, a cabinet 2702, a display portion 2703, a voice input portion2704, a voice output portion 2705, an operation key 2706, an outsideconnection port 2707 and an antenna 2708. The cellular phone isfabricated by using the liquid display device fabricated by theinvention at the display portion 2703. Further, the display portion 2703can restrain power consumption of the cellular phone by displaying acharacter of white color on the background of black color.

As described above, the range of applying the liquid crystal displaydevice fabricated according to the invention is extremely wide andelectronic apparatus in all the fields can be fabricated. Further, theelectronic apparatus of the embodiment can be made by using the liquidcrystal display device fabricated by carrying out Example 1 throughExample 5.

By the above, by carrying out the present invention, because thescatterbility of light can be enhanced by forming a concavo-convexstructure with using a transparent electrode and reflection electrode inthe manufacture of a transflective type liquid crystal display device,display visibility can be improved. Also, because a plurality ofisland-like patterns to be made into a reflection electrode can beformed simultaneously with interconnections by etching a conductivefilm, it is possible to realize a great cost reduction and improvementin productivity.

1. A liquid crystal display device comprising: a transparent conductivefilm formed on an insulating surface; and an interconnection and aplurality of island-like conductive films that are formed on thetransparent conductive film, wherein the plurality of island-likeconductive films are irregularly arranged on the transparent conductivefilm, wherein the transparent conductive film, the interconnection andthe plurality of island-like conductive films are electricallyconnected, and wherein the plurality of island-like conductive filmstogether have an area ratio of 50–90% of an area occupied by thetransparent conductive film.
 2. A liquid crystal display deviceaccording to claim 1, wherein the plurality of island-like conductivefilms each has a pattern end having a taper angle of 5–60 degrees.
 3. Aliquid crystal display device according to claim 1, wherein thetransparent conductive film comprises at least one material selectedfrom the group consisting of indium tin oxide, indium oxide and zincoxide.
 4. A liquid crystal display device according to claim 1, whereinthe liquid crystal display device is incorporated into an electronicapparatus selected from the group consisting of a digital still camera,a notebook personal computer, a mobile computer, a portable type imagereproducing apparatus having a recording medium, a video camera and acellular phone.
 5. A liquid crystal display device comprising: atransparent conductive film formed on an insulating surface; and aninterconnection and a plurality of island-like conductive films that aresimultaneously formed on the transparent conductive film, wherein theplurality of island-like conductive films are irregularly arranged onthe transparent conductive film, wherein the transparent conductivefilm, the interconnection and the plurality of island-like conductivefilms are electrically connected, and wherein the plurality ofisland-like conductive films together have an area ratio of 50–90% of anarea occupied by the transparent conductive film.
 6. A liquid crystaldisplay device according to claim 5, wherein the plurality ofisland-like conductive films each has a pattern end having a taper angleof 5–60 degrees.
 7. A liquid crystal display device according to claim5, wherein the transparent conductive film comprises at least onematerial selected from the group consisting of indium tin oxide, indiumoxide and zinc oxide.
 8. A liquid crystal display device according toclaim 5, wherein the liquid crystal display device is incorporated intoan electronic apparatus selected from the group consisting of a digitalstill camera, a notebook personal computer, a mobile computer, aportable type image reproducing apparatus having a recording medium, avideo camera and a cellular phone.
 9. A liquid crystal display deviceaccording to claim 1, wherein the transparent conductive film is a pixelelectrode.
 10. A liquid crystal display device according to claim 5,wherein the transparent conductive film is a pixel electrode.
 11. Aliquid crystal display device comprising: a transparent conductive filmformed on an insulating surface; and a plurality of island-likeconductive films formed on the transparent conductive film, wherein theplurality of island-like conductive films are irregularly arranged onthe transparent conductive film, and wherein the plurality ofisland-like conductive films together have an area ratio of 50–90% of anarea occupied by the transparent conductive film.
 12. A liquid crystaldisplay device according to claim 11, wherein the plurality ofisland-like conductive films each has a pattern end having a taper angleof 5–60 degrees.
 13. A liquid crystal display device according to claim11, wherein the transparent conductive film comprises at least onematerial selected from the group consisting of indium tin oxide, indiumoxide and zinc oxide.
 14. A liquid crystal display device according toclaim 11, wherein the liquid crystal display device is incorporated intoan electronic apparatus selected from the group consisting of a digitalstill camera, a notebook personal computer, a mobile computer, aportable type image reproducing apparatus having a recording medium, avideo camera and a cellular phone.